An event handler that reacts to the events 'Create' and 'Update', i.e. 'Saving' an entity (see Common action event) is configured as shown on the right:

• The Validating rule (collapsed in the image) uses a Check type to ensure that a 'product catalog entry' is present as the reference object. The productCatalogId is also checked via an AND junction using an Entity property rule in order to check whether the entry belongs to the Product catalog that is 'predefined' according to the request.
  
  

• As an Action on passed rule, a For each loop event action is executed. The basis for the loop is a list of all price attributes for the product referenced in the product catalog entry (see Products), which is restricted as described below to the price attributes for which no Tax rate has yet been specified and for whose 'Country' a default tax rate is stored.
  
  

• Within the loop, a simple assignment to the Object property 'Tax rate' (taxRate) is made for all relevant price attributes. The internal name for the Tax rate in question is systematically constructed by Concat strings from the value for the Object property 'Country' (country) of the price attribute and the static suffix '_default' defined by the arbitrary convention.
  
  ►NOTE◄ Since the configuration for the Resolver for entities (see below) ensures that the loop will only execute price attributes for which a suitable Tax rate exists, automatic type conversion from text value to enumeration value can be set here without further provisions.

The Resolver for entities, which defines the basis for iteration within the loop, is configured as a concatenation of value resolvers as shown on the right:

• In the first step, the Object property value resolver must be used to evaluate the product field, which refers to a product in the product catalog entry
  
  

• Within the product, the All attributes of one type value resolver is used, in which the Attribute type 'Price attribute' must be selected here. The return value is a list of all price attributes found for the product.
  
  

• The list of all price attributes is restricted by the concatenated Rule list resolver to Resolve all as list for which the following conditions are met:
  

  • The first condition is that the 'Tax rate' (taxRate) field of the price attribute does not contain a value yet (see Entity property rule and Is empty). For example, if a price attribute has already been assigned a tax rate that differs from the default, this selection remains unchanged.
    
    

  • The second AND-linked junction ensures that a default Tax rate is stored for the 'Country' (country) to which the price attribute applies by definition. This check is configured in the example as a With rule, where the internal name is constructed in the Entity property resolver by Concat strings, which according to convention applies to the default Tax rate of the respective country:
    
    

    • First (similar to the assignment in the Set value event action, see above) the static suffix '_default' is added to the internal name in the country field.
      
      

    • This string is passed to an Input object (type safe) value resolver. Since the selected Type of Tax rate is a dynamic enumeration, an incoming text value is interpreted as an internal 'Name' within this enumeration and the corresponding enumeration value is returned (otherwise: 'no value').
      
      

    • In the rule definition of the With rule, a Check type can therefore be performed on the Tax rate type, which is passed only if a Tax rate is stored that corresponds to the 'Name' structured according to the convention.

The Rule list resolver returns a list of all price attributes of the product for which a default tax rate can be assigned. The assignment is only performed for these within the loop (see above).

►NOTE◄ Products are Referenced objects, so changes to attributes of a product referenced in a product catalog entry do not change the properties of that product if it has already been saved. Rather, when saving, the system checks whether the changed feature combination corresponds to an existing product. Otherwise, this product will be automatically recreated. Then the reference in the product catalog entry is changed to the existing or newly created product. Existing references, e.g. in items of business objects or other product catalogs, continue to refer to the original product.